docs(dropdowntree): Add info when a postback is triggered by the control

Author: pepinho24

controls/dropdowntree/server-side-programming/events/onentryadded.md

@@ -14,7 +14,7 @@ position: 2
 
 ## 
 
-The server-side **OnEntryAdded** event occurs when an entry is added to the entry area, causing a postback.
+The server-side **OnEntryAdded** event occurs when an entry is added to the entry area, causing a postback. The postback is triggered when the dropdown is closed. To close the dropdown when a node is selected, you can set DropDownSettings-CloseDropDownOnSelection="true".
 
 The event handler receives two parameters:
 

controls/dropdowntree/server-side-programming/events/onentryremoved.md

@@ -14,7 +14,7 @@ position: 3
 
 ## 
 
-The server-side **OnEntryRemoved** event occurs when an entry is removed from the entry area, causing a postback.
+The server-side **OnEntryRemoved** event occurs when an entry is removed from the entry area, causing a postback. The postback is triggered when the dropdown is closed. To close the dropdown when a node is selected, you can set DropDownSettings-CloseDropDownOnSelection="true".
 
 The event handler receives two parameters:
 

controls/dropdowntree/server-side-programming/events/overview.md

@@ -18,6 +18,6 @@ RadDropDownTree control introduces the following server-side events for working
 
 * [NodeDataBound]({%slug dropdowntree/server-side-programming/events/nodedatabound%}) - Occurs when the nodes in the tree in the dropdown are bound.
 
-* [EntryAdded]({%slug dropdowntree/server-side-programming/events/onentryadded%}) - Occurs when an entry is added.
+* [EntryAdded]({%slug dropdowntree/server-side-programming/events/onentryadded%}) - Occurs when an entry is added. The postback is triggered when the dropdown is closed. To close the dropdown when a node is selected, you can set DropDownSettings-CloseDropDownOnSelection="true".
 
-* [EntryRemoved]({%slug dropdowntree/server-side-programming/events/onentryremoved%}) - Occurs when an entry is removed.
+* [EntryRemoved]({%slug dropdowntree/server-side-programming/events/onentryremoved%}) - Occurs when an entry is removed. The postback is triggered when the dropdown is closed. To close the dropdown when a node is selected, you can set DropDownSettings-CloseDropDownOnSelection="true".